<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            box-sizing: border-box;
            width: 100px;
            height: 100px;
            /*径向渐变*/
            background-image: radial-gradient(red, yellow, pink);
            margin: 12px 29px 36px 24px;
            padding: 18px 33px 21px 16px;
            border: 1px solid red;
        }
    </style>
</head>

<body>
    <div>边框盒子</div>
</body>

</html>